This invention relates to air compressors; and more particularly relates to a novel and improved swash plate air compressor conformable for use with air tanks of varying sizes and configurations which can be positively but releasably attached to each air tank according to the intended application.
In the past, air compressors have borrowed from conventional combustion engine designs while reversing the typical energy cycle to convert mechanical energy into pneumatic energy. Indeed, most prior air compressors utilize conventional crankshaft technology to drive pistons and thus suffer numerous drawbacks relating to energy conversion, size and weight, as well as the noise associated with operation of such compressors.
With the advent of smaller motors, the size and weight of compressors have gradually been reduced, allowing portable compressors to be attached to relatively small air tanks. However, such portable compressors still typically rely on traditional crank shaft technology and thus trade power for size so that most portable compressors can not achieve substantial volume at high pressure within the attached air tank. Furthermore, even with their reduced size, such portable air compressors and their associated air tanks represent heavy, cumbersome assemblies which strain the definition of the term "portable."
A further drawback to current compressors is that the compressor is typically mated with a single air tank and can not be easily adapted to work with other air tanks. Thus, current portable compressors are often relegated to being used with small air tanks which may be too small to hold a useful volume of pressurized air for the required task. Similarly, larger non-portable air tanks are typically mated with large compressors which can not be easily moved.
Previously, efforts have been made to substitute swash plate technology for the more conventional crank shaft technology within air compressors. Swash plate compressors utilize a wobbling disk connected to a drive shaft to reciprocate the pistons within the air cylinders. Due to the relatively small size of most air compressors (at least in relation to the size of an internal combustion engine), the use of a wobble or swash plate to drive the pistons has led to increased efficiencies due to the decreased angle of the piston connecting rod which is attached to the swash plate and the mechanical flow of energy. In essence, the swash plate provides a truer reciprocating action for the piston rods than is possible with conventional crank shafts. This has led to the introduction of oil or lubricant-free compressors due to the reduced strain applied by the swash plate to the piston connecting rods which results in reduced friction between the pistons and cylinders.
However, these early swash plate compressors have failed to adequately address the added degree of motion which the swash plate imposes on the piston connecting rod in comparison to a traditional crank shaft. In essence, the wobbling motion of the swash plate causes a periphery of the swash plate to follow a wave-like or figure-8 pattern which results from the combination of a first arcuate motion of the swash plate periphery toward and away from the drive shaft and a second rolling motion of the swash plate periphery about an axis perpendicular to the drive shaft. To account for this figure-8 pattern, the end of the piston connecting rod which is connected to the swash plate must be free to move in two different directions (i.e., rotate about two different axes) to prevent over-stressing the piston rods. While some designs have attempted to provide for this freedom of movement by replacing traditional piston connecting rod, bearings and wrist pins with ball and socket connectors or other similar joints, these joints have failed to provide an adequate connection between the swash plate and the piston rod, particularly when the compressor is required to achieve high pressures or is operated over extended duty cycles. Specifically, prior swash plate compressors utilizing ball and socket connectors are typically not suitable to generate relatively high pressures (e.g., 90 p.s.i. and above) and are extremely susceptible to piston rod failure.
Representative of such prior swash plate compressors are those disclosed in U.S. Pat. No. 2,825,499 to Gibson et al., U.S. Pat. No. 4,495,855 to Murakami et al., U.S. Pat. No. 5,109,754 to Shaw, and U.S. Pat. No. 5,304,043 to Shilling, each of which use ball and socket connectors or similar swivel elements within the swash plate to engage the piston connecting rods. Other patents of interest include U.S. Pat. No. 4,734,013 to Valavaara, U.S. Pat. No. 5,127,314 to Swain, U.S. Pat. No. 2,956,845 to Wahlmark, and U.S. Pat. No. 2,412,316 to Campbell.
Therefore, a continuing need exists for a portable, lightweight, high-power air compressor system that overcomes the above and other limitations of prior art air compressors. A need also exists for an air compressor which can be selectively and interchanbeably utilized with different sizes and configurations of air tanks to accommodate the different needs of different end users. It is with respect to these and other background considerations, limitations and problems, that the present invention has evolved.